BacA is indispensable for successful Mesorhizobium-Astragalus symbiosis.

A homologue of Sinorhizobium meliloti bacA was isolated from Mesorhizobium huakuii 7653R, which is capable of fixing atmospheric nitrogen in symbiotic association with leguminous Astragalus sinicus (Chinese milk vetch). Inactivation of the bacA gene abolished the ability of M. huakuii 7653R to establish a successful symbiosis with its host plant.